First Atlantic satellite tracks of lost years green turtles support the importance of the Sargasso Sea as a sea turtle nursery

In-water behaviour and long-term movements of oceanic-stage juvenile sea
turtles are not well described or quantified. This is due to technological
or logistical limitations of tracking small, fast-growing animals across
long distances and time-periods within marine habitats. Here we present
the first long-term offshore tracks of oceanic green turtles (Chelonia
mydas) in western North Atlantic waters. Using a tag attachment technique
developed specifically for young (<1 year old) green turtles, we
satellite tracked 21 oceanic-stage green turtles (<19 cm straight
carapace length) up to 152 days using small, solar-powered transmitters.
We verify that oceanic-stage green turtles: (i) travel to and remain
within oceanic waters; (ii) often depart the Gulf Stream and North
Atlantic Subtropical Gyre currents, orienting toward waters associated
with the Sargasso Sea; (iii) remain at the sea surface, using
thermally-beneficial habitats that promote growth and survival of young
turtles; and (iv) green turtles orient differently compared to same stage
loggerhead turtles (Caretta caretta). Combined with satellite tracks of
oceanic-stage loggerhead turtles, our work identifies the Sargasso Sea as
an important nursery habitat for North Atlantic sea turtles, supporting a
growing body of research that suggests oceanic-stage sea turtles are
behaviourally more complex than previously assumed.